[moaningmags]

Are the machines Vista, XP or a combination of both?

In the Netgear page under Advanced Settings, do you have UPnP?
Is it ticked?
Mine has the following
Turn UPnP On (ticked)
Advertisement Period (in minutes) 30
Advertisement Time To Live (in hops) 4

UPnP Portmap Table
Active Protocol Int. Port Ext. Port IP Address
YES UDP 52577 52577 192.168.1.3
YES TCP 33521 33521 192.168.1.6
YES UDP 33521 33521 192.168.1.6
YES TCP 59965 59965 192.168.1.6
YES UDP 50386 50386 192.168.1.5
YES TCP 56431 56431 192.168.1.5
YES UDP 59466 59466 192.168.1.7
YES TCP 53409 53409 192.168.1.7
YES TCP 49449 49449 192.168.1.4